1. Field of the Invention
This invention relates to apparatus to adjust the position of the rear axle or axles of a semi-trailer in a direction parallel to the longitudinal axis of the semi-trailer, so as to vary the weight distribution between said axle or axles and the axle or axles of the tractor. More particularly, this invention relates to motorized means to position the axle or axles of a semi-trailer forward or rearward, as may be required to produce a desired weight distribution between the axles of the semi-trailer and the axles of the tractor, and to then secure the semi-trailer axles.
2. Description of Related Art
In the trucking industry, in order to protect road surfaces and bed, various weight regulations are generally imposed. At least some of these regulations pertain not only to the total amount of weight that may be carried, nor to only the total amount of weight that may be carried by a certain tractor/trailer assembly, but also to the amount of weight borne by each axle of the tractor/trailer assembly. Thus a certain load may be well within the overall weight regulations of a certain tractor/trailer assembly, but still cannot be legally transported by that tractor/trailer assembly unless the weight distribution of the load between the several axles of the assembly can be brought within applicable weight per axle regulations.
Generally when a certain load is otherwise within regulation weight but not within weight per axle regulations the transporter's options are limited to:
i) carriage of the load by a different tractor/trailer assembly (having a greater number of axles, more evenly distributing the weight of the load); PA1 ii) disassembling the load into smaller components to be separately carried; PA1 iii) shifting the position of the load or various components thereof on the trailer; or PA1 iv) shifting the position of one or more axles of the trailer relative to the position of the load on the trailer.
By far the most frequent method used to redistribute the weight of the load between the several axles of the tractor/trailer assembly is to shift the position of the axle or axles of the semi-trailer, either forward or rearward, as required to bring the weight borne by each axle within applicable regulatory limits. Typically such shifting of the position of the axle or axles of a semi-trailer is done by manual means which include releasing the axles to be able to slide along the longitude of the trailer within a pair of guide beams disposed beneath the trailer bed, securing (usually with chocks on the wheels) the axle or axles of the semi-trailer against movement and then (usually pulling or pushing the trailer with the tractor), attempting to move the trailer, usually while loaded, either forward or backward to a desired position over the chocked axle or axles. This method typically requires at least two persons, one operating the tractor, and one monitoring the relative positions of the trailer and axle(s) and signalling the tractor operator which direction to move the trailer and when to stop. Precise movement of the trailer position relative to the axle(s) of the trailer can be difficult to accomplish using said method and frequently involves jerking the trailer with the tractor, particularly when a heavy load is on the trailer. Yet despite the difficulty in attaining it, precise positioning of the trailer relative to the position of the axle(s) is usually required, if not to achieve the precise weight distribution, at least to re-secure the axle(s) to the trailer (typically by pin means which require precise alignment of pairs of holes in the axle carriage assembly and the trailer bed frame).
Therefore, an object of the present invention is to provide an improved apparatus for redistributing the weight of a load being carried by a tractor/semi-trailer assembly between the axle or axles of a semi-trailer and the axles of the tractor. More particularly, another object of the present invention is to provide an improved apparatus for shifting the position of the axle or axles of a semi-trailer relative to the position of the bed frame of said semi-trailer. With more specificity objects of the present invention are to provide a motorized means whereby a single operator can smoothly, expeditiously and safely position and secure the axle or axles of a semi-trailer precisely, at a variety of precise incremental positions within a range of necessary axle positions.